The present invention relates to a scroll type compressor.
In general, a scroll type compressor includes a fixed scroll member having a fixed end plate and a fixed scroll wall and a movable scroll member having a movable end plate and a movable scroll wall. The fixed and the movable scroll members are disposed in a housing of the compressor with the scroll walls thereof engaged with each other. The movable scroll member orbits around the axis of the fixed scroll member and refrigerant gas drawn into a compression chamber formed between the fixed and the movable scroll walls of the scroll members is compressed with a decrease in the volume of the compression chamber in accordance with the orbital motion of the movable scroll member relative to the fixed scroll member.
Japanese Patent Application Publications H9-273488 and H11-148470 disclose a scroll type compressor that has a rib provided on the side of the fixed end plate that is opposite from the side thereof where the fixed scroll wall is formed. Japanese Patent Application Publication H9-273488 disclose a scroll type compressor having a first rib provided at the center on one side of the fixed end plate, a plurality of second ribs provided on the same side of the fixed end plate and extending radially from the first rib and a third rib provided adjacently to the outer periphery of the fixed end plate and connected with the second ribs. Japanese Patent Application Publication H11-148470 disclose a scroll type compressor having a first rib provided on one side of the fixed end plate so as to surround the discharge port and a plurality of second ribs extending radially from the first rib.
In the scroll type compressors of the above Publications, the compression chamber formed between the fixed and the movable scroll walls of the scroll members is moved toward the center while reducing its volume in accordance with the orbital motion of the movable scroll member. Refrigerant in the compression chamber is compressed and discharged out therefrom through the discharge port into a discharge chamber. The compressed and hence high-pressure refrigerant is used in the refrigerant circuit for the air conditioning. The ribs in the scroll type compressors disclosed in the above-cited Publications prevent the fixed scroll member from being deformed by the compressed high-pressure refrigerant.
Japanese Patent Application Publication 2006-118511 discloses a scroll type compressor that has the discharge chamber and an oil storage chamber between the housing and the fixed scroll member. In this scroll type compressor, the discharge chamber and the oil storage chamber are separated from each other by a separation wall formed behind the fixed end plate and a separation wall formed in the front of the housing.
In a scroll type compressor, it is difficult to strike a balance between increasing the amount of the refrigerant discharged per one orbital motion of the movable scroll member and the on-board capability.
If the winding angle of the fixed scroll wall and the movable scroll wall is increased with an attempt to increase the amount of the refrigerant discharged per one orbital motion of the movable scroll member, the size of the compressor is enlarged only for the sacrifice of the on-board capability. Meanwhile, if the height of the fixed scroll wall and the movable scroll wall is enlarged with an attempt to increase the amount of the refrigerant discharged per one orbital motion of the movable scroll member, there is a fear that the strength of the center portion of the movable scroll member and fixed scroll member may be impaired. If the thickness of the fixed end plate and the movable end plate is enlarged for the increasing the strength of the center portion of the movable scroll member and fixed scroll member, the size of the compressor is enlarged and, therefore, the on-board capability is impaired.
In the scroll type compressor of the above Publication, the rib or the separation wall of the fixed end plate is provided irrespective of the inner end of the fixed scroll wall. Therefore, there has been a problem in that the size of the compressor is enlarged and the on-board capability is decreased.
The present invention is directed to providing a scroll type compressor that can strike a balance between increasing the amount of refrigerant discharged per one orbital motion of the movable scroll member and the on-board capability.